From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luca Ceresoli Date: Mon, 14 Sep 2015 18:07:09 +0200 Subject: [Buildroot] [RFC 3/6] system: add mdev-only /dev management (without devtmpfs) In-Reply-To: <55F09799.6030609@mind.be> References: <1441747734-18730-1-git-send-email-luca@lucaceresoli.net> <1441747734-18730-4-git-send-email-luca@lucaceresoli.net> <20150909132929.5c01433e@free-electrons.com> <55F09799.6030609@mind.be> Message-ID: <55F6F0AD.6020704@lucaceresoli.net> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Dear Arnout, Arnout Vandecappelle wrote: > On 09-09-15 13:29, Thomas Petazzoni wrote: >> Luca, >> >> On Tue, 8 Sep 2015 23:28:51 +0200, Luca Ceresoli wrote: >>> There are a few reasons for an embedded Linux system not to use devtmpfs, >>> but still want to have dynamic /dev management. The most notable is to use >>> a kernel < 2.6.32, which have no devtmpfs support. >>> >>> For such corner cases, we introduce the ability to use busybox mdev for >>> /dev management even without devtmpfs. >>> >>> First, we need the BR2_ROOTFS_STATIC_DEVICE_TABLE just like the static >>> /dev management, in order to have the very basic devices such as /dev/null >>> and /dev/console until mdev is enabled. >> >> As said in another e-mail, this is not really true: we just need a very >> simple, two devices long, hard-coded device table. There is no need to >> allow the user to customize it. It would in fact be potentially >> misleading because the user who would add more devices in this static >> device table would not see them on the target: they would be >> "overridden" by the tmpfs mounted in /dev. > > Right! So: > > define BUSYBOX_DEVICES > /dev/console c 666 0 0 5 1 - - - > /dev/null c 666 0 0 1 3 0 0 - > endef Good idea, this saves creating a new device table. -- Luca